DEAR DR. FOX: After reading your column about what to do when a gentle dog turns aggressive, I decided to share the following saga with you:

My dog, P.D., a 6 1/2-year-old 27-pound neutered mixed-breed dog, had always been a sweetie. When we got him, he was about 10 to 12 weeks old, and had 52 ticks on his little body. As a pup and young dog, topical flea and tick preventatives made him sick, so for the ensuing years we have fed him brewer's yeast and garlic tablets.

He has never had fleas or ticks during that time. However, after applying Frontline Tritak on him -- as required by a boarding kennel -- his behavior suddenly and drastically changed for the worse. The scientific literature search below will explain what we learned and how P.D. returned to his normal, sweet self. Approximately 60 days after the Frontline was discontinued, his aggressive behavior completely stopped. It has not reoccurred.

I'm including part of what I have learned about fipronil, the main active ingredient in Frontline Tritak for dogs.

An Australian study, conducted on behalf of the Australian Pesticides and Veterinary Medicines Authority (APVMA), reports about dogs treated with fipronil: "Neurological clinical signs included ataxia, lethargy and two instances of biting or aggression. Gastrointestinal signs included vomiting and diarrhea."

From the Journal of Pesticide Reform: "fipronil is a relatively new insecticide. It is used in cockroach baits and gels, flea products for pets, ant baits and gels, termite control products, turf and golf course products, and agricultural products. ... In pets, poisoning symptoms include irritation, lethargy, incoordination, and convulsions. ... In tests with laboratory animals, fipronil caused aggressive behavior, damaged kidneys, and 'drastic alterations in thyroid function.' The fipronil-containing product Frontline caused changes in the levels of sex hormones.

"The offspring of laboratory animals exposed to fipronil during pregnancy were smaller than those of unexposed mothers. They also took longer to mature sexually.

"The U.S. Environmental Protection Agency classifies fipronil as a carcinogen because exposure to fipronil caused benign and malignant thyroid tumors in laboratory animals.

"One of fipronil's breakdown products is ten times more toxic than fipronil itself.

"People can be exposed to fipronil when they pet an animal that has received a flea treatment. Fipronil persists for at least 56 days on pets.

"Studies of fipronil contamination of water are limited, but it has been found in rivers near rice fields where it is used in Louisiana. It has also been found in an urban stream in Washington.

"Fipronil is toxic to birds, lizards, fish, crawfish, shrimp, bees, and other animals. Minute concentrations (as low as five parts per trillion) have caused adverse effects."

I believe, and my vet agrees: Fipronil is what caused P.D.'s aggressive behavior. -- B.B., St. Louis

DEAR B.B.: I very much appreciate your observations and possible confirmation of the anti-flea product making your dog become aggressive. The aggression could have been fear-induced because the fipronil made your dog more fearful or anxious. He could engage in so-called defensive fear-biting, with possible involvement of the adrenal glands, or be more irritable and prone to offensive aggression, which could have been due to the drug's effects on the thyroid gland or central nervous system.

Fiprinol is one of a class of chemicals that block nerve conduction (so-called GABA-gated chloride channels) to which many species of insect are highly susceptible. Merck drug company is promoting Bravecto, a new oral drug for dogs that kills fleas and ticks, available only from veterinarians. The company claims that one dose works for 12 weeks, and that it is safe for pregnant and lactating dogs. It reports that the most common adverse reactions recorded in clinical trials were vomiting, decreased appetite, diarrhea, lethargy, polydipsia and flatulence. The active insecticide in this product is an isoxazoline called fluralaner, which is in the same isoxazoline class of insecticides as Fiprinol. The same is true of the drug afoxolaner in Merial's NexGard.

Your research summary findings on Fiprinol, available to anyone with Internet access, support my quest for a sane, safe and effective approach to flea control, as detailed in the review article posted on my website, DrFoxVet.com. Consumers in general, and the pet-owning public in particular, need to be more mindful and questioning rather than trusting what they are told by manufacturers and our government regulatory authorities.

(Send all mail to animaldocfox@gmail.com or to Dr. Michael Fox in care of Universal Uclick, 1130 Walnut St., Kansas City, MO 64106. The volume of mail received prohibits personal replies, but questions and comments of general interest will be discussed in future columns.

Visit Dr. Fox's website at DrFoxVet.com.)

DEAR DR. FOX: Why is your book "Not Fit for a Dog" not in the library system in Denver and surrounding area, nor in Prospector materials databases and interlibrary loan? -- A.L., Denver

DEAR A.L.: Thanks for your email on a very important issue for authors -- not about making money, for me at least, but all about getting the message out to help improve the health and well-being of our animal companions as well as those who love and care for them.

There are many reasons why libraries don't carry certain titles (mine being mainly in the nonfiction area, although I have received literary awards for some of my children's fiction books). These reasons range from increasingly limited budgets to assumed lack of public readership interest. In some backward areas, it's even a case of censorship.

I know that many of my books have been pilloried by the animal industry complex. One sector of this complex, which my book "Not Fit for a Dog!: The Truth About Manufactured Cat & Dog Food," co-authored with two other veterinarians, criticizes and urges to improve pet food quality and safety, has much money to use for lobbying and political influence. This sector even put my job on the line, complaining about me to one particular CEO of the Humane Society of the United States in the late 1990s when I began investigating what goes into pet foods.

Some people who like a particular book and want to share it with others will donate it to the library. If you prefer, you could ask the librarian to pull up the book title on the Internet and see if he or she would consider carrying it. Then take it from there.

DEAR DR.FOX: Thank you so much for answering. I finally did find your book in a different library system. I'll be persistent with my own library to buy the book. There's also an excerpt of "Not Fit for a Dog" on the library website that condenses your book and tells a lot of important information. I've had a huge vendetta with Purina, whose name I can barely get out, because growing up I had a black Lab on Purina who had kidney disease by age 6. Photos of the dog at 5 and 6 years look like he's only half alive. He lived to be 7.

Maybe people can get educated. Many have blind faith in advertisements that companies take advantage of. Additionally, some people may feel that dogs shouldn't get expensive food -- it is part of our Puritan ethic against frivolousness. I can't thank you enough for writing. I'm sure my county library will buy your book. Thank you for your bravery as the harassment I'm sure has been immense. -- A.L., Denver

SOCIALLY ISOLATED PARROTS AGE FASTER THAN THOSE IN GROUPS

If you feel sad or mad seeing "pet" parrots living alone, isolated from their own kind, then you are right on the mark! Telomeres act as a protective cap on the ends of chromosomes and have been likened to the binding on the ends of shoelaces that prevent shredding. These telomeres degrade with age, and a team of Austrian veterinarians and others has provided the first evidence that social isolation affects telomere length.

African gray parrots bred in captivity and raised alone seemed to age faster because they had shorter telomeres compared to those raised in pairs or groups. This supports the investigators' hypothesis that telomeres provide a marker indicating exposure to chronic stress and may be a better indicator of measuring stress in nonhuman animals than measuring corticosteroid stress hormone levels.

These findings support my long-held contention that the common practice of keeping various highly social species as solitary pets, which often makes them abnormally attached to humans, is both harmful and ethically questionable. For a penetrating critique of the animal industry complex and of currently condoned ways of keeping animals for pleasure and profit, see "Slaves of Our Affection: The Myth of the Happy Pet," by veterinarian Dr. Charles Danten. The author tells me that he was inspired by my earlier book, "Inhumane Society: The American Way of Exploiting Animals."

(Send all mail to animaldocfox@gmail.com or to Dr. Michael Fox in care of Universal Uclick, 1130 Walnut St., Kansas City, MO 64106. The volume of mail received prohibits personal replies, but questions and comments of general interest will be discussed in future columns.

Visit Dr. Fox's website at DrFoxVet.com.)

DEAR DR. FOX: I'm having a problem with my barn cat. This cat, Samson, moved into my barn last spring. I had him neutered, and he has his shots.

Samson became so aggressive with my other barn cats that I moved them to my house. Samson now attacks me when I walk away from the barn. I thought that he needed more attention, but that only seems to make the situation worse. Sometimes I pull a string so he attacks it instead. Today he attacked me with teeth and nails, and I had a difficult time getting him to stop. What do I do? -- S.S., Potomac, Maryland

DEAR S.S.: I understand why you had to move your other cats indoors after this domineering interloper took over and became such a bully. This must have been a stressful adjustment for them as well as you.

Changing Samson's name to Sammy won't make him more of a gentleman, just as neutering a cat later in life won't erase domineering and aggressive behavior patterns and some aspects of sexual behavior. Neutering before sexual maturity and experience does make a big difference, according to early behavioral research by the late Dr. Lester Aronson, whose research on cat sexual behavior was extremely controversial from an animal welfare and ethics perspective.

Many cats play ambush games and bat at your legs as you are walking by. This is their invitation to play and often comes from a life of boredom, which, to some degree, can be alleviated by playing chase and other interactive games. Samson's behavior is in another category since he is showing uninhibited attack or predation behavior toward you.

I would say goodbye to Samson for the greater good of your barn cat colony and your own peace of mind -- and health. Cat bites can mean hospitalization for blood poisoning (Pasteurella bacterial sepsis), and cat-scratch fever can develop from infected claws, with painful lymph node swelling misdiagnosed in more than one instance by human doctors unfamiliar with zoonotic diseases (animal-to-human transmitted infections) as lymphatic cancer!

An expert feline behavioral therapist might rehabilitate Samson once any possible underlying disease is ruled out, notably hyperthyroidism, which can make some cats more aggressive.

DEAR DR. FOX: Four weeks ago, I added a new member to my family: a 9-week-old rough-coat collie.

He gets 1/2 cup of dry dog food in the morning and again in the evening. The problem is that he does not chew his food, he inhales it -- it is gone in a few seconds. I have gone online, called the vet, have had an in-home instructor, but nothing helps. I have a divider in his food bowl, but it doesn't work. I put his food in a ball with a hole in the side that drops it out a piece at a time.

I am aware collies are prone to bloat, so I'm trying to fix this problem now. Any advice would be greatly appreciated. -- C.C., Springfield, Missouri

DEAR C.C.: I urge you to read up about proper puppy care and feeding, because two half-cups of dry dog food (and you do not indicate what brand and if it is formulated for puppies) is not enough. He most likely "inhales" his food because he is ravenous.

He should be fed at least four small meals daily. Give him 1/2 cup of dry, canned or home-prepared food at each meal. He needs high-quality protein and fat, with balanced calcium and other mineral and vitamin supplements. Be sure that a stool sample is checked for worms, which often infest pups and rob the animal of essential nutrients.

DEAR DR. FOX: I would like to get a small adult dog. I am handicapped and use a walker to walk, and I live in an apartment. I hope to be able to train the dog to go to the bathroom on a paper pad.

Some members of my family insist that I should not get a dog. They think that I will not be able to care for a dog because I will not be able to take the dog outside in the winter for walks (I live in northern Minnesota). I feel that a dog will be fine because I have plenty of room in my apartment to exercise and play games. Is it OK to have a dog in these circumstances? I would really appreciate your advice. -- J.C., Duluth, Minnesota

DEAR J.C.: Putting the best interests of the dog before yours, ask yourself why you want a dog? If it is animal companionship, adopt a cat if you are not allergic. Cats do not need to go outdoors, are 95 percent easier to train to evacuate indoors in a litter box and with all the interactive toys available, you can engage in stimulating games with the cat from the sofa or wheelchair. Dogs need to get out and run around, even in winter.

While you consider the best animal companion for you, think adoption first; also, consider getting two cats. Two cats will care for each other and give you hours of entertainment and devotion.

(Send all mail to animaldocfox@gmail.com or to Dr. Michael Fox in care of Universal Uclick, 1130 Walnut St., Kansas City, MO 64106. The volume of mail received prohibits personal replies, but questions and comments of general interest will be discussed in future columns.

Visit Dr. Fox's website at DrFoxVet.com.)